Gelled nitromethane composition

ABSTRACT

A process for the production of a gelled explosive composition of nitromethane, inorganic nitrate, a water or methanol fluid medium, and gelling agents therefor, comprising mixing said nitromethane and said fluid medium, adding with thorough agitation said inorganic nitrate, a gelling agent for the fluid medium and a cyanoethyl ether of galactomannan gum gelling agent for the nitromethane.

Unite States Patent [19] Edwards [111 3,765,966 [451 Oct. 16, 1973GELLED NITROMETHANE COMPOSITION [75] Inventor: Donald W. Edwards,Lehighton, Pa.

[73] Assignee: Commercial Solvents Corporation,

Terre Haute, Ind

22 Filed: July 21,1972

21 Appl. No.: 274,118

[52] US. Cl 149/18, 149/21, 149/47,

149/60, 149/62, 149/89 [51] Int. Cl. C06b 7/00, C06b 19/04 [58] Field ofSearch 149/2, 18, 89

[56] References Cited UNITED STATES PATENTS 3,419,444 12/1968 Minnick,.l49/89X 5/1972 Jordan 149/89 10/1972 Edwards 149/89 X PrimaryExaminer-Leland A. Sebastian Att0rneyI-loward E. Post et a].

[5 7] ABSTRACT 7 Claims, No Drawings GELLED NITROMETHANE COMPOSITIONBACKGROUND OF THE INVENTION This invention relates to gelled slurryexplosive compositions. In a particular aspect, this invention relatesto gelled nitromethane-inorganic nitrate slurry compositions and methodof preparing same.

It is known from L. R. Jones, U.S. Pat. No. 3,318,741, to provide stablegels of nitromethane by adding from 0.5 to 10 percent or more of a highmolecular weight polyoxyethylene and from 0.1 to 5.0 percent ofpoly(methylvinylether/maleic anhydride).

Aqueous slurries of ammonium nitrate and nitromethane were disclosed byJ. J. Minnick, US. Pat. No. 3,4l9,444. Compositions disclosed included10-90 percent ammonium nitrate, -50 percent water, 5-50 percentnitromethane. According to Minnick, the nitromethane is first gelled byblending 5 percent nitrocellulose (or the agent of Jones) therein. Then,the ammonium nitrate, resin balloon sensitizer, water, and guar gumthickening agent were added. Other suitable thickeners for the aqueousphase included gum arabic, pregelatinized starch and carboxymethylcellulose.

Recently W. A. Jordon disclosed in U.S. Pat. No. 3,666,577 thatcyanoethyl ethers of galactomannan gums having a degree of substitutionof 1.9 or more are effective gelling agents for nitromethane in amountsof about 2 percent or more. Jordon suggests the gelled nitromethane isuseful in explosives by incorporating therewith an inorganic nitrate anda sensitizing explosive such as TNT.

The above-described processes are essentially twostep wherein thenitromethane is first gelled, then the ammonium nitrate, water andgelling agent therefor are added. This method is disadvantageous becausethe gelled nitromethane is difficult to blend uniformly with the otheringredients and requires prolonged mixing. There is, therefore, a needfor an improved method of blending.

SUMMARY OF THE INVENTION It is an object of this invention to provide animproved method for preparing explosive compositions.

It is another object of this invention to provide an improved method forthe preparation of gelled nitromethane-inorganic nitrate water-basedslurries.

Other objects of this invention will be obvious to those skilled in theart from the description herein.

It is the discovery of this invention to provide a process for thepreparation of explosive gels of nitromethane and inorganic nitrate in afluid medium by the steps of mixing the liquid, i.e., the nitromethaneand fluid medium, then adding the solid ingredients, i.e., the inorganicnitrate, a gelling agent for the fluid medium, and a gelling agent forthe nitromethane, and mixing thoroughly. Preferably a tetraalkyltitanate crosslinking agent for the nitromethane is also added.

DETAILED DESCRIPTION The process of the present invention is essentiallya one-step process. The liquids, i.e., nitromethane and fluid medium,are charged to a kettle, then the solids are added with thoroughagitation to provide good mixing. If desired, the solids can be premixedbefore adding to the solid phase, but no advantage is gained thereby.The mixture initially forms a thick slurry, then after standing for ashort time, develops into a gel.

There is ample time for casting or loading into suitable containers.

The nitromethane employed in the practice of this invention is the usualgrade of commerce and is used in an amount of about 10-15 percent byweight, preferably l5 percent. The liquid medium is water or methanol,preferably water, and is used in an amount of about 10 percent byweight.

The inorganic nitrate used in the practice of this invention can beeither sodium nitrate or ammonium nitrate or a mixture thereof. Theammonium nitrate can be either low density or high density prills orgranular ammonium nitrate sold commercially as fertilizer grade. Groundmaterial can also be used. Preferably the particle size is sufficientlysmall that it passes a 20 mesh screen. When water is used, it can besaturated with ammonium nitrate to provide a portion of ammonium nitratein solution form, if desired.

The gelling agent employed for gelling the aqueous phase can be any ofthe gelling agents known in the prior art of which there are many.Preferred gelling agents include guar gum, gum arabic, pregelatinizedstarch and carboxymethyl cellulose. Guar gum is preferred. When methanolis used as the fluid medium, the preferred gelling agent is methylcellulose.

The gelling agent employed for gelling the nitromethane is a cyanoethylether of a galactomannan gum having a degree of substitution of greaterthan 1.9, as disclosed by W. A. Jordon, U.S. Pat. No. 3,666,577 which isincorporated herein by reference. This material is sold by GeneralMills, Inc. as GM-5l2.

The gels prepared with the foregoing ingredients have sufficientstability for most applications but they begin to break down afterseveral weeks. Firmer and more stable gels can be obtained bycross-linking the GM-5 l2 gelling agent with a tetraalkyl titanate, e.g. tetraisopropyl or tetrabutyl titanate. These compounds arecommercially available and the usual commercial grades are suitable forthe practice of this invention. Tetraisopropyl titanate is somewhatfaster than tetrabutyl titanate, but use of the latter permits longerworking time, e.g. for casting or loading into containers.

The nitromethane-inorganic nitrate gel is rendered detonable by shock byincorporating therein a sensitizer, many of which are known, asdescribed by Minnick, U.S. Pat. No. 3,419,444. Preferred sensitizers areglass or resin microballoons.

The practice of this invention will be better understood with referenceto the following examples. It is understood that the examples areintended only to illustrate the practice of the invention and it is notintended that the invention be limited thereby.

EXAMPLE 1 To a mixing kettle were charged the following liquidingredients:

Nitromethane 15.00 lb Aqueous ammonium nitrate Soln., 20.00 50% wt.

The following solid ingredients were added thereto with mixing:

Ammonium nitrate, granular l/l6" 60.l0 lb Glass microballoons 2.00Cross-linking agent 2.00 GM-5 l2 gelling agent 0.50 Guar gum gellingagent 0.40

EXAMPLE 2 The experiment of Example l was repeated in all es sentialdetails except that the solid ingredients were premixed before adding tothe liquids. The mixture formed a thick slurry which became a firm gelafter standing a short period of time. It was detonable by the shock ofa No. 6 blasting cap.

EXAMPLE 3 To a mixing kettle were charged the following liquidingredients:

10.0 lb l0.0

Nitromethane Methanol The following ingredients were added with mixing:

Sodium nitrate 10.0 lb Ammonium nitrate 64.7 Glass microballoons 3.0Cross-linking agent 1.5 Methyl cellulose 0.4 GM-5l2 gelling agent 0.4

The mixture initially formed a thick slurry which became a firm gelafter standing a short period of time. It was detonable by the shock ofa 10 g booster of pentolite combined with a 6 blasting cap.

The methyl cellulose was Methocel 65 H-6 manufactured by Dow ChemicalCompany, Midland, Michigan. 4

EXAMPLE 4 The experiment of Example 3 was repeated in all es sentialdetails except that the nitromethane content was increased to 15 lbinstead of 10, and the ammonium nitrate content was decreased to 59.7 lbfrom 64.7.

The resultant gel was detonable by a 10 g booster and a 6 blasting cap.

The glass microballoons used in the foregoing examples are hollowspheres of sodium borosilicate glass, 10-300 microns in diameter,manufactured by Emerson and Cuming, Inc., Canton, Massachusetts.

I claim:

1. In a process for the production of a gelled explosive composition ofnitromethane, an inorganic nitrate, a water or methanol fluid medium andgelling agents therefor, the improvement consisting of adding to amixture of said nitromethane and said fluid medium, with thoroughagitation, a mixture of said inorganic nitrate, a gelling agent for thefluid medium and a cyanoethyl ether of galactomannan gum gelling agentfor the nitromethane.

2. The process of claim 1 wherein said inorganic nitrate is ammoniumnitrate.

3. The process of claim 1 wherein said inorganic nitrate is a mixture ofsodium nitrate and ammonium nitrate.

4. The process of claim 1 wherein said fluid medium is water.

5. The process of claim 1 wherein said fluid medium is methanol.

6. The process of claim 1 wherein said fluid medium is water saturatedwith ammonium nitrate.

7. The process of claim 1 wherein additionally a tetraalkyl titanatecross-linking agent for the cyanoethyl ether of galactomannan gum isincorporated therewith in said composition.

* g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent {765966 I Dated October 16, 1973 Inven fl Donald W. Edwards lt is certifiedthat eirror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 24, "Jordon" should be -Jordan-' Column 2, line 29,"Jordon" should be -Jordan-- Colunm 3, line 38, "a 6" should be --a #6Column 4, line 9 "a 6" should be --a #6-' Signed and sealed this 9th dayof April 19m.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer v Commissionerof Patents 22 3 33 C UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent 1165 966 Dated October 16, 1973 Invent fl Donald W.Edwards 7 It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 24, "Jordon" should be Jordan-' Column 2, line 29,"Jordon" should be -Jordan- Column 3, line 38, "a 6" should be a- #6Column 4, line 9, "a 6" should be a #6-- Signed and sealed this 9th dayof April 197i;

(SEAL) Attest:

EDWARD M.FLETCHER,JR. G. MARSHALL DANN Attesting Officer Commissioner ofPatents

2. The process of claim 1 wherein said inorganic nitrate is ammoniumnitrate.
 3. The process of claim 1 wherein said inorganic nitrate is amixture of sodium nitrate and ammonium nitrate.
 4. The process of claim1 wherein said fluid medium is water.
 5. The process of claim 1 whereinsaid fluid medium is methanol.
 6. The process of claim 1 wherein saidfluid medium is water saturated with ammonium nitrate.
 7. The process ofclaim 1 wherein additionally a tetraalkyl titanate cross-linking agentfor the cyanoethyl ether of galactomannan gum is incorporated therewithin said composition.